Hydraulically operated drop hammer



Aug. 9, 1932. w, ERNgT 1,870,499

HYDRAULICALLY OPERATED DROP HAMMER Filed June 18, 1929 2 Sheets-Sheet l I" 4 l L 63 Z1: 57

(Ittornega Aug. 9, 1932. w. E-RNST 1,870,499

HYDRAULICALLY OPERATED DROP: HAMMER Filed June.l8, 1929 2 Sheets-Sheet 2 v attorneys,

Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE WALTER ERNST, or MOUNT GILEAD, omoAssmnoa-ro HYDRAULIC rREss MANU- r'acrniune COMPANY, or MOUNT GILEAD, 01110 *EYDRAULICALLY OPERATED DBOiE' HAMMER Application filed June 18,

a blow upon the object or material being.

worked. a

At present there are two well known kinds of dropv hammers, namely, those commonly known as board hammers and those operated by means of a compressible fluid such as air or steam. Each of the above named types of hammers is subject to certain disadvantages.

Board hammers are provided with one or more boards which are secured to the upper side of the hammer and which extend upwardly between a pair of parallel rolls adapted to be moved towards each other to frictionally engage the board or boards, and to thereby lift the latter together with the hammer. When the hammerreaches a predetermined height the rolls are disengaged from the boards andthe hammerdrops upon the work below by gravity. This type of drop hammer is subject to numerous troubles such as misalinement of the rolls and the hammer with resulting premature breaking of the boards, high friction losses due to the drive for the rolls, and also to the high cost of board replacements, the boards even in a perfectly alined machine requiring frequent replacement.

Steam operated drop hammers include a steam cylinder and a piston mounted therein and connected to the hammer for raising the v latter to its upper position upon the admission of steam into the cylinder. When the hammer is in this position and it is desired to strike a blow upon the work, the cylinder is opened to an exhaust and the hammer then falls by gravity. Of course such hammers require a boiler plant which is not always available, especially in small shops, so that the use of such hammers is limited.

Air operated drop hammers are arranged to operate in a manner similar to that in which steam drop hammers work, the chief difierence being that compressed air, instead of v stem, is used as a pressure fluid. In shops using a number of air hammers it is custom: i

1929. Serial No. 371,777.

ary to provide a single compressor having a capacity sufliciently large to supply the needs of all of the several drop hammers. This is because of the fact that, as is well known,it is more economical to compress-air in large quantities than in smallquantities.

With such a single source of air supply,the

large compressor must be kept running regardless of whether one or all of the hammers are being operated, a'nd this, of course, results in both a high overhead expense and high operating expense when the shop is being run at anything below its peak capacity.

An object of the present invention is to overcome the above mentioned disadvantages by the provision of inexpensive hydraulic means including a minimum number of moving parts and adapted to raise a drop hammer preparatory to striking a blow, and to then permit the hammer to fall gravitationally upon the material or object being Worked. Other objects of the invention will be apparent from a reading of the following description, the appended claims, and the several views illustrated in the drawings, in which:

' Figure 1 is a front elevation of a drop hammer embodying my invention with parts shown in section;

Figure 2 is a diagrammatic view of the by draulic circuit showing a four-way valve in the position it occupies when the hammer is being raised;' j

Figure 3 is a view similar to Figure 2 but showing the valve in another position;

Figure 4 is a fragmentary vertical sectional view of a valve operating cam and associated parts; and

Figure 5 is a view taken at right angles to Figure 4 and showing the cam in elevation.

Hydraulic hammer operating means em bodying my invention may be used in connection with drop hammers of various'different constructions but my invention isherein illustrated and described as being applied to a 'drop hammer includinga frame comprising an anvil or base A, a head B which is connected to the base by means of two vertical posts C, and} a hammer D slidably mounted on the posts for reciprocatory movements towards and away from the base.

For raising the hammer preparatory to its being allowed to drop toward the base or anvil, I provide a vertically disposed cylinder 1 supported on the head B and positioned directly above the hammer, a reciprocable piston 2 slidably mounted in the cylinder and connected to the hammer by means of a piston rod 3 extending through the lower end .of the cylinder, and hydraulic means for furnishing the lower or pressure end of the cylinder with fluid under pressure. M

These hydraulic means include a pump 4 driven by a motor 5, the suction side of the pump being in constant communication with a fluid supply tank 6 through the medium of a pump suction pipe 7 and the discharge end of a pump being connected to a four-way. valve 8 by means of a supply line 9. The

valve 8 in turn is arranged to communicate through'the casing and spaced 90 degrees apart, these ports ing in constant communication with the pipes 910-11 and 12 respectively. w

In order that the discharge from the pump be first directed into the pressure end of the cylinder to raise the piston and the hammer and to subsequently by-pass the discharge 1 of the pump directly to the tank and at the same time to place the pressure end of the f cylinder in communication with the tank so as to permit the hammer to descend by gravity, the valve rotor 14 is provided with two sepprate passages 19 and 20 respectively, w 'ch passages extend laterally through the rotor and open at the periphery thereof at four points 90 degrees apart.

It will be seen that when the valve rotor is in the position shown in Figure 2 the discharge from the umpwill be directed to the pressure end 0 the cylinder by means of the supply line 9, the passage 20 in the valve rotor, an the combined inlet and outlet .pipe

10. When the valve rotor is turned through 90 degrees in a counter-clockwise direction,

as viewedin Figure 2, itwill occupy the position' shown in Fi re 3, in which position of the rotor the discharge fromthe pump will be bypassed to the tank by means of the supply piper9, the rotor passage 1g, and the by-pass pipe 12; and at the same time the pressure end of the cylinder Wlll communicate with'the tank through the medium of the pipe 10, the rotor passage 20, and the exhaust pipe 11.

It-is to be understood that the pressure fluid is utilized only for raising the piston and the hammer preparatory to the gravitational fall thereof, and for this reason the pressure fluid is introduced into the lower end of the cylinder only and not into the upper end thereof. In order that the fluid entering the lower end of the cylinder will be returned to the tank after the piston and hammer have reached a predetermined point on their upward stroke, I provide a cylinder relief pipe 21 having one of its ends connected to the cylinder at a point adjacent the upper end thereof but spaced from the upper end at a distance greater than the thickness of the piston 2, and having its other end connected to the tank. It will be seen that after the piston, when on its upward stroke, moves past the point at which the pipe 21 is connected to the cylinder, the fluid pressure in the cylinder will be relieved and the fluid will pass out of the cylinder and will return to the tank by means of the cylinder relief pipe.

It is desirable that means be provided for bringing the piston and the hammer to rest gently after the piston has passed the point of connection between the cylinder and the relief pipe. To this end the-upper end of the cylinder is closed by means of a cylinder head 21a and the cylinder wall is provided with a vent 22 located adjacent to but spaced from the upper end of the cylinder. That portion of the cylinder which is included between the head 21a and the vent 22 constitutes a dash pot in which air is entra ped when the piston has ascended to a height to cover the vent, the entrapped air then acting to cushion the upward movement of the piston and to bring the latter and thehammer to restgently after the piston has passed beyond the relief pipe 21. The vent-22 also constitutes a means for egress of air from the upper end of the cylinder when the piston is moving upwardly, so that air not be forced out through the relief pipe and into the tank, and also serves to admit air to the upper end ofthe cylinder when the piston is on its down stroke, thereby avoiding the sucking of fluid from the tank into the relief pi 3nd thence into the upper end of the cy er. a I p In order that the valve rotor will be automatically moved when the hammer approaches the end of its down stroke, valve I operatingemeans are arranged in cooperating Y tween the valve and the hammer.-

and to this end I secure the valve to thebase A b means-of bolts 23.

a valve is so positioned that the rotor It I is movable about a vertical axis; and connect-- ed to the rotor and coaxial therewith 18 a moving the rock shaft.

toward the right as viewed in Figure 1, terminating short of the bottom of the sleeve and merging with the lower end of a straight vertically extending groove 28, which is open at the upper end of the sleeve. 1

- A lug 29 of a s'ze adapted to enter an pass along the grooves 27 and 28 is secured to the hammer and is so positioned that, when the shaft and sleeve are in the position shown in Figure 1, and the hammer is caused to descend, the lug will enter the groove 27 at the upper end thereof, and upon further descent of the hammer the lug will cam the vsleeve through approximately 90 degrees in a counter-clockwise direction, thereby moving the valve rotor into the position shown in Figure 2. The pump discharge will then be directed into the pressure end of the cylinder and the piston and hammer will begin to ascend. During the firstpart of the up stroke of the hammer the lug 29 will pass up through the straight groove 28 without lVhen the piston reaches the position shown in Figure 1, it will be brought to rest as. described above and will then continue to dwell in this position until the valve rotor is moved to the position shown in Figure 3.

For moving the valve to the Figure 3 position, the rock shaft 24 is provided with a manually operable lever secured to the lower end of the shaft so as to be within convenient reach of the operator. When the valve rotor is in the. position shown in Figure 2 and it is desired to move the valve into the position shown in Figures 1 and 3, the

' rock shaft is'turned in a counter-clockwise direction as viewed in Figure2 by means of the lever 30, after which the pipe 10 will be connected to the exhaust pipe 11 and the hammer will descend.

Operation 5 the pipe 10,. and thence into the pressure end of the cylinder. Since the piston is positioned above the point of connection between the relief pipe 21 and the cylinder, the fluid will leave the cylinder and flow through the relief pipe into the tank, the piston being thereby held stationary and caused to dwell in its uppermost position.

lVhen it is desired that the hammer descend to strike a blow upon the object or material being worked, the rock shaft 24 is turned through 90 in a counter-clockwise direction as viewed in Figure 2 through the medium of the manually operable lever 30.

This movement of the valve rotor will place the latter in theposition shown in Figures 1 and 3 wherein the discharge from the supply line is directed through the passage 19 and the by-pass pipe 12 and thence into tank 6; and at the same time the pressure end of the cylinder is placed in communication with the tank 6 through the medium of the pipe 10, the valve rotor passage 20 and the exhaust pipell. Thehammerwillthendescendgravitationally, and during its descent will force the fluid contained in the cylinder back into the tank. When the hammer approaches the end of its down stroke the lug 29 will enter the helical groove 27 and will turn the shaft 24 through 90 in a clockwise direction there by returning the valve rotor to the Figure 2 position at which time the discharge'from the pump will be directed into the pressure end of the cylinder, and the piston and hammer will begin their upstroke. As has been already described the lug 29 will pass up along the straight groove-28 during the first part of the upstroke without moving the rock shaft. During the upstroke of the piston, air

contained in the upper end of the cylinder will be forced out through the vent 22 and after the vent has been covered bythe piston the air entrapped between the piston and the cylinder head will be compressed and will finally bring the piston and hammer to rest in a position above the relief pipe 21 in which position the fluid entering the pressure end of the cylinder will be returned to the tank by means of the relief pipe and the, hammer will dwell in its upper position until the valve is again manually moved to the Figure 3 position. I

From the foregoing'it is apparent that I have provided simple and efiicient hydraulic means for elevating a drop hammer. The pump, valve mechanism, 'and associated piping is compact and includes a minimum number of moving parts, which naturally results in a low maintenance cost. The pump is small as compared to air compressors used in connection with air operated drop hammers, and consequently the cost of the initial installation is considerably less.

I claim:

1. In a self-contained hydraulic drop hanimer unit, the combination with a vertically ';reciprocable hammer; of a cylinder having a pressure end and a closed end; a piston mounted for reciprocatory movements in the cyhnder and connected to the hammer; a pump; an operating motor for the pump;

-. 'and means forming with the pump and the 4 cylinder a closed hydraulic circuit including v the piston and the hammer and for placing a pump suction pipe a supply pipe for receiving discharge from the pump, an exhaust pipe, a combined inletand outlet pipe connected at one of its ends to the pressure end of the cylinder, the opposite end of said pipe being adapted to communicate separately with both the supply pipe and the exhaust pipe, a valve movable to two positions'for placing the combined inletwand outlet pipe in communication with the supply pipe to raise said combined inlet and outlet pipe in come munication with said exhaust pipe when the hammer is in its upper position for effecting a dro of the hammer; a relief pipe having I one 0 its ends arranged to communicate with the pump suction pipe and having its other end arranged to communicate with the cylinder at a point adjacent the closed end th e reof but spaced from said closed end at a dismeans forming with the pum'p'an-d'the cylinder a closed hydraulic circuit including a pump suction pipe, a supply pipe forreceiving discharge.v fromthe pump, an exhaust pipe, a combined inlet and outlet pipe connected at one of its ends to the pressure end of -the cylinder, the opposite end of said pipe being adapted to vcommunicate separately with both the supply pipe and the exhaust pipe, a valve movable to two positions for placing the combined inlet and outlet pipe in communication with thesupply pipe tov raise the iston and the hammer and for) lacing said combined inlet and outlet pipe in communication with saidexhaust pipe pipe; means for operating said valve; and said cylinder having a vent beyond the zone of connection of the relief pipe thereto and adjacent said closed end of the cylinder but spaced therefrom to avoid sucking of fluid bination with a vertically reciprocable ham mer; of a cylinder; a piston mounted for reciprocatory movements in the cylinder and connected to the hammer; a pump; means forming with'the pump and the cylinder a hydraulic circuitincluding a pum suction pipe, a supply pipe for receiving ischarge from the pump, an exhaust pipe, means for first connecting one end of the cylinder to the supply pipe to raise the piston and the hammer and for then connecting said end.

of the'cylinder to the exhaust pipe whereby the hammer will descend by'gravity a relief pipe having one of its ends arranged to communicate "with the pump suction pipe-and having its other end arranged to communicate with a cylinder at a point adjacent the closed end thereof but spaced from said closed end at a distance greater than the thickness of the piston, whereby, when the hammer is raised to its uppermost position, pressure fluid will be returned to the pump suction pipe, and a cylinder vent ad acent said closed end of the cylinder and spaced therefrom and disposed between said closed end and the point of connection between the relief pipe and the cylinder, said vent being adapted to be covered by the-piston when the hammer approaches its uppermost position to thereby provide a dashpot for bringing the piston and the hammer to rest gently.

In testimony whereof, I have hereunto subscribed my name.

' WALTER ERNST.

when the hammer is in its upper position for effecting a drop of the hammer; a relief'pipe having one of its-ends arranged to communicate with the pump suction pipe and having its other end arranged to communicate with the cylinder at a point adjacent the closed end thereof but spaced from said closed end at a distance greater than the thickness of the piston, whereby, when the hammer is raised to its uppermost position, pressure fluid willbereturned to the pump suction 3. In a hydraulic drop hammer, the COm- 

